In this photo provided by Touchstone Pictures, Oliver (Ashton Kutcher) and Emily (Amanda Peet), are good friends until they realize they may just be right for each other romantically in "A Lot Like Love." (Touchstone Pictures/Demmie Todd)

Romantic comedies have become way too chaste to satisfy those of us who grew up watching couples uninhibitedly couple on the big screen, sometimes before even being properly introduced. So it seems like old times when strangers mate midair in the privy of a plane in "A Lot Like Love" -- a romantic tale with a lot going for it besides an acknowledgment that carnal knowledge hasn't altogether slipped the minds of the younger generation.

An unfortunate casting decision, however, comes close to sabotaging a witty script with fresh insights into the trend of young people postponing marriage while waiting for some grand plan of theirs to materialize. It can be a long wait, evidenced by those acrobatic lovers, Oliver and Emily. That first tryst, initiated by Emily to prove she still has it after a boyfriend breaks up with her, results in an on-again, off-again affair lasting the next seven years.

As the sometimes couple, Ashton Kutcher and Amanda Peet are together in almost every scene, making it difficult to conceal the huge gap in their acting skills. Bland and with a small television face (words once used to describe David Caruso, but equally applicable here), Kutcher is incapable of doing the heavy lifting required to be a romantic lead. If he and Peet were performing a pas de deux, she would wind up in the hospital with multiple fractures. Peet, who has the looks and magnetism of a Kennedy offspring, makes Kutcher fade into the background, and you're left fantasizing what the movie might have been if Peter Sarsgaard had co-starred.

Still, the movie is rich in the kind of details often left out because of a lack of budget or imagination. Emily and Oliver have fully fleshed out lives, including parents, siblings and career aspirations. Much is revealed about Emily when she visits the grave of her mother, who, the tombstone shows, died at 37. With a brisk brushing away of tears, Peet conveys the lasting impact of this loss.

The vagaries of the dot-com world are pretty accurately portrayed through Oliver's entrepreneurial attempt to sell diapers on the Internet. He tries to make a go of it in San Francisco, naturally, although none of the movie was shot here. Oliver sounds as if he's barely out of diapers himself during a halting presentation to a group of venture capitalists. Nonetheless, his company is awarded $6 million; a year later it goes bust.

This puts a crimp in the life plan he describes in great detail to Emily. They talk like real people, thanks to the good ear of screenwriter Colin Patrick Lynch. Even Kutcher can handle the charmingly silly moments concocted to show that Emily and Oliver are kindred spirits. Their spitting match in a Japanese restaurant is a lot funnier than it sounds.

"Love" strains credibility, though, with a multitude of coincidences that hook the pair up again after they have parted ways, such as his wandering by a gallery exhibiting her photos, including a naked one of them snapped years earlier. An array of secondary characters never quite comes alive, especially those who temporarily claim Oliver and Emily's affections but obviously aren't right for them.

British director Nigel Cole, who proved he could handle comedy in "Saving Grace" and "Calendar Girls," keeps "Love" clipping along. He makes such effective use of New York and Los Angeles, showcasing parts rarely captured onscreen, that you wish he had ventured all the way to San Francisco.